1. Field of the Invention
The present invention relates to agents, drinks and food products for improving lipid metabolism and reducing high blood pressure and the combination thereof that are effective in treating and preventing diseases such as fatty liver, hyperlipidemia, arteriosclerosis, obesity and hypertension.
2. Description of the Related Art
Lipid metabolism refers to catabolic (decomposing) and anabolic (accumulating) in vivo processes of lipids, mainly comprising triglicerides derived from food. Lipid metabolism generally includes energy-releasing reaction of lipids, biosynthesis of fatty acids, biosynthesis of acylglycerols, phospholipid metabolism, cholesterol metabolism, and the like (“Biochemistry for Nutrition” by Akira Misaki, Asakura Shoten, 1993, pp. 123-134).
In recent years, the mortality rate from cardiovascular disease has been rapidly increasing and the correlation between the risk of getting cardiovascular disease and the blood cholesterol concentration has been pointed out. Meantime, several attempts have been made to reduce the blood cholesterol concentration by using food materials, which can be ingested in daily life. For example, soybean protein (Arteriosclerosis 1988 72:115), whey protein (Agric Biol Chem 1991 55:813; Japanese Patent Application Laid-open No. H5-176713), soybean protein hydrolyzates (J Nutr 1990 120:977), and egg yolk phospholipid (Agric Biol Chem 1989 53:2469) have been tried. Further, a method making use of lactoalbumin, collagen, soybean protein or wheat gluten and soybean lecithin in combination (Nutr Rep Int 1983 28:621) and a method making use of tissue-like soybean protein containing soybean lecithin (Ann Nutr Metab 1985 29:348), and the like have been proposed.
High blood pressure refers to essential hypertension, etiology of which is unknown, and secondary hypertension, which is associated with disease of the kidney, adrenal gland or nervous system. In recent years, 90% of cases are reported to be essential hypertension. Today, antihypertensive agents are frequently used for the prevention and treatment of essential hypertension. However, every conventional antihypertensive agent has a disadvantage to show a certain adverse effect. For example, individual drugs show characteristic adverse effects: antihypertensive diuretics cause hypokaliemia or acidemia, antihypertensive peripheral vasodilators cause hypoglobulia, β-blockers cause bronchoasthma, and α-methyldopa increases glutamic-oxaloacetic transaminase (GOT) or glutamic-pyruvic transaminase (GPT) values in the blood and causes hemolytic anemia. Accordingly, a special consideration is required in administering these antihypertensive agents, and the dosage and period of administration for these agents are naturally restricted.
Under the abovementioned circumstances, development of antihypertensive agents without adverse effects has been strongly urged, and antihypertensive agents having a microorganism-derived substance as an effective component have drawn attention. Such substances comprise, for example, high molecular weight polysaccharides derived from lactic acid bacteria as an effective component (Japanese Patent Application Laid-open No. S59-190929), glycoproteins having a molecular weight of more than 10,000 isolated from chlorella algae (Japanese Patent Application Laid-open No. S60-45603), viable or dead cells of bacteria of genus Streptococcus (Japanese Patent Application Laid-open S61-221124), dried beer yeast as an effective component (Japanese Patent Application Laid-open No. S63-255234), or a hot water extract of lactic acid bacteria (Japanese Patent Application Laid-open S63-139129; Japanese Patent Application Laid-open No. H2-247127). However, many of these substances are water insoluble and have unpleasant taste, which prevent them from practical use.
Therefore, attempts have been made to develop antihypertensive agents comprising substances contained in food materials, which can be administered orally in daily life, as an effective component. For example, an enzyme-digested casein product (Food Develop 1997 32:37-39), and an enzyme-digested fish meat product (Health Nutr Food Res 1998 1:62-71; Food Develop 1996 31:50-52) have been reported.
However, the methods described above have problems such that a relatively large amount of ingestion is required, that flavor is not desirable, and that precipitation occurs during storage when made into drinks interfering with stable storage.
More importantly, no substance which can improves lipid metabolism and reduce high blood pressure simultaneously is known. A problem in lipid metabolism can be a cause of raising blood pressure, and in that case, inadequate lipid metabolism is associated with high blood pressure. For example, in some cases, high blood cholesterol levels tend to cause arteriosclerosis which leads to high blood pressure. Thus, if a substance which can both improve lipid metabolism and reduce high blood pressure is developed, the problem in both lipid metabolism and blood pressure can effectively be resolved.